| LCI | Laboratory of Clinical Investigation | In English | → Research institutes → Medicine |
| LCIE | Laboratoire Central des Industries Électriques | In English | → Research institutes → Electrical engineering |
| LCM | Logic Control Modeler | In English | |
| LCM | Liquid Crystal Mete | In English | |
| LCM | Least Common Multiple | In English | → Mathematics |
| LCM | Linz Center of Mechatronics | In English | → Electrical engineering |
| LCMS | Low-Cost Modular Spacecraft | In English | → Spaceflight engineering, astronautics |
| LCMS | The Lutheran Church - Missouri Synod (www.lcms.org) | In English | → Protestant churches |
| LCMS | Learning Content Management System | In English | → Knowledge management → Education |
| LCMV | Lymphocytic Choriomeningitis Virus | In English | → Virology |
| LCN | Logic Change Notice | In English | |
| LCN | Loosely Coupled Network | In English | |
| LCN | Logistics Control Number | In English | → Maintenance and logistics |
| LCOM | Logic Control Output Module | In English | |
| LCR | Low Cross Range | In English | |
| LCROSS | Lunar Crater Observation and Sensing Satellite | In English | → Astronomy → Spaceflight engineering, astronautics |
| LCS | Launch Control System | In English | → Spaceflight engineering, astronautics |
| LCS | List of Command Signals | In English | |
| LCS | Libyan Cardiac Society | In English | → Organizations and associations → Cardiology |
| LCSW | Licensed Clinical Social Worker | In English | → Social welfare → Medicine → Psychology |
| LCU | Line Coupling Unit | In English | |
| LCU | Load Control Unit | In English | |
| LCUG | Liquid Cooling Undergarment | In English | |
| LCV | Logistics Cargo Vehicle | In English | → Maintenance and logistics → Vehicle engineering |
| LCVG | Liquid Cooling (and) Ventilation Garment | In English | |
| LDA | Local Density Approximation | In English | → Atomic physics |
| LDA | Latvian Development Agency | In English | → 33972 |
| LDA | Lithuanian Development Agency | In English | → 33972 |
| LDAP | Lightweight Directory Access Protocol | In English | → Networks, communication |
| LDB | Launch Data Bus | In English | |
| LDB | Logistics Data Bank | In English | → Data → Maintenance and logistics |
| LDC | Lot Date Code | In English | |
| LDC | Less Developed Country | In English | → Development → Geography |
| LDCs | Least Developed Countries | In English | |
| LDD | Logical Data Base Design | In English | → Data |
| LDD | Land Degradation & Development | In English | → Serial publications, periodicals → Agricultural sciences |
| LDEC | Lunar Docking Events Controller | In English | → Spaceflight engineering, astronautics |
| LDEF | Long-Duration Exposure Facility | In English | |
| LDEF | Long Duration Exposure Facility | In English | |
| LDFX | Little Daughters of Saint Francis Xavier | In English | → Roman catholic church |
| LDH | Lactate Dehydrogenase | In English | → Enzymes |
| LDIU | Launch Data Interface Unit | In English | → Human-computer interaction → Spaceflight engineering, astronautics |
| LDL | Low Density Lipoprotein | In English | → Biochemistry, biophysics |
| LDL | Low-Density Lipoprotein | In English | → Biochemistry, biophysics |
| LDLR | Low-Density Lipoprotein Receptor | In English | → Biochemistry, biophysics |
| LDP | Large Deployable Reflector | In English | |
| LDP | Local Data Package | In English | → Data |
| LDR | Low Data Rate | In English | → Data |
| LDRP | Logistics Depot Repair Procedure | In English | → Maintenance and logistics |
| LDS | Landing, Deservicing, and Safing | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| LDS | Launch Detection Satellite | In English | → Spaceflight engineering, astronautics |
| LDS | Layered Defense System | In English | → Military engineering |
| LDS | Laser Docking Sensor | In English | |
| LDSJG | Little Daughters of Saint John Gaulbert | In English | → Roman catholic church |
| LDT | Linear Displacement Transducer | In English | |
| LDT | Level Detector | In English | |
| LDZ | Lithium-Depleted Zone | In English | |
| LE | Leading Edge | In English | |
| LE | Launch Escape | In English | |
| LE | Linguistic Engineering | In English | → Linguistics |
| LE | London Electricity | In English | → Electrical engineering |
| LEA | Logistics Engineering Analysis | In English | → Maintenance and logistics → Engineering, technology |
| LEA | Local Education Authority | In English | → Public administration, government → Education |
| LEA/MP | Logistics Engineering Analysis and Maintenance Planning | In English | → Maintenance and logistics → Engineering, technology |
| LEAD | Live Early Adoption and Demonstration | In English | |
| LEADS | LWIR Exoatmospheric Discrimination Study | In English | |
| LEAP | Lightweight Exoatmospheric Projectile | In English | → Military engineering |
| LEC | Lockheed Electronics Company | In English | → Electronics |
| LEC | Large Engines Competence Center | In English | |
| LED | Light-Emitting Diode | In English | → Electronics |
| LEDC | Low-Energy Detonating Charge | In English | → Military engineering |
| LEDC | Less Economically Developed Country | In English | → Development → Geography |
| LEDI | Low Endoatmospheric Defense Interceptor | In English | → Military engineering |
| LEE | Locus of Enterocyte Effacement | In English | → Blood and circulatory system → Pathology |
| LEFM | Linear Elasticity Fracture Mechanics | In English | → Physics |
| LEG | London Electricity Group | In English | → Electrical engineering |
| LEGMA | Latvian Environment, Geological and Meterological Agency | In English | → Nature → Environment, environmental sciences → Earth sciences → Meteorology, climatology |
| LEH | Launch and Entry Helmet | In English | → Spaceflight engineering, astronautics |
| LEI | Lithuanian Energy Institute | In English | → Energy economics |
| LEID | Low-Energy Ion Detector | In English | |
| LEM | Laboratory Environment Model | In English | |
| LEM | Launch Escape Monitor | In English | → Spaceflight engineering, astronautics |
| LEM | Lunar Excursion Module | In English | → Planets and satellites → Spaceflight engineering, astronautics |
| LEND | Lunar Exploration Neutron Detector | In English | → Astronomy |
| LEO | Low Earth Orbit | In English | → Astronomy → Spaceflight engineering, astronautics |
| LEO | Librating Equidistant Observer | In English | |
| LER | Lunar Eyepiece Receptacle | In English | |
| LeRC | Lewis Research Center | In English | |
| LERC | Lebanese Emigration Research Center | In English | → Migrations |
| LES | Leading Edge Subsystem | In English | |
| LES | Launch Equipment Shop | In English | → Spaceflight engineering, astronautics |
| LES | Launch Escape Subsystem | In English | → Spaceflight engineering, astronautics |
| LES | Launch-Entry Suit | In English | → Spaceflight engineering, astronautics |
| LES | Lincoln Experimental Satellite | In English | → Spaceflight engineering, astronautics |
| LES | Logistic Execution System | In English | → Maintenance and logistics |
| LESS | Leading Edge Structural Subsystem | In English | |
| LET | Linear Energy Transfer | In English | |
| LETCO | Liberian Eastern Timber Corporation | In English | → Forestry → Timber and woodworking industry |
| LETF | Launch Equipment Test Facility | In English | → Spaceflight engineering, astronautics |
| LETIT | Local Energy Technology Implementation | In English | → Energy economics |
| LETS | Leiden Thrombophilia Study | In English | → Pharmacology, toxicology → Pathology |
| LEV | Lunar Excursion Vehicle | In English | → Spaceflight engineering, astronautics |
| LF | Launch Facility | In English | → Spaceflight engineering, astronautics |
| LF | Low Frequency | In English | |
| LF | Load Factor | In English | |
| LFAF | Low-Frequency Accelerometer Flutter | In English | |
| LFAM | Low-Frequency Accelerometer Modes | In English | |
| LFAP | Low-Frequency Accelerometer Pogo | In English | |
| LFC | Large Format Camera | In English | |
| LFIB | Libyan Foreign Investment Board | In English | → 33972 |
| LFM | Local Focus Mechanism | In English | |
| LFO | Low-Frequency Oscillator | In English | |
| LFOP | Landing and Ferry Operations Panel | In English | → Vehicle engineering |
| LFRR | Low-Frequency Radio Range | In English | → Telecommunications |
| LFT | Lufthansa Flight Training GmbH | In English | → Aeronautics, aircraft → Transport and postal services |
| LFV | Lunar Flying Vehicle | In English | → Spaceflight engineering, astronautics |
| LG | Landing Gear | In English | |
| LGA | Low-Gain Antenna | In English | → Telecommunications |
| LGI | Local Government and Public Service Reform Initiative | In English | → Municipal administration |
| LGL | Lethal Giant Larvae | In English | → Zoology |
| LGS | Landing Gear Subsystem | In English | → Spaceflight engineering, astronautics |
| LGTA | Landing Gear Test Article | In English | → Spaceflight engineering, astronautics |
| LH | Luteinizing Hormone | In English | → Hormones → Gynaecology |
| LH | Lateral Hypodermis | In English | → Medicine |
| LHA | Local Hour Angle | In English | |
| LHC | Left-Hand Circular | In English | → Optics |
| LHCP | Left-Hand Circular Polarization | In English | → Optics |
| LHFEB | Left-Hand Forward Equipment Bay | In English | |
| LHMT | Letters Heat Mass Transfer | In English | → Serial publications, periodicals → Thermodynamics |
| LHOP | Laser-Hardened Optical Payload | In English | |
| LHP | Left-Hand Panel | In English | |
| LHRCS | Left-Hand Reaction Control System | In English | |
| LHRLA | Lawyers for Human Rights and Legal Aid | In English | → Organizations and associations → Law, jurisprudence → Fundamental rights |
| LHS | Left-Hand Side | In English | |
| LHSC | Left-Hand Side Console | In English | |
| LI | Laser Illuminator | In English | |
| Li | Lithium = Li | Litium | In Afrikaans = Li | ليثيوم | In Arabic = Li | Litiu | In Asturian = Li | Літый | In Belarusian = Li | Литий | In Bulgarian = Li | লিথিয়াম | In Bengali = Li | Litijum | In Bosnian = Li | Liti | In Catalan = Li | Litiu | In Corsican = Li | Lithium | In Czech = Li | Лити | In Chuvash = Li | Lithiwm | In Welsh = Li | Lithium | In Danish = Li | Lithium | In German = Li | Λίθιο | In Greek = Li | Litio | In Esperanto = Li | Litio | In Spanish = Li | Liitium | In Estonian = Li | Litio | In Basque = Li | لیتیوم | In Persian = Li | Litium | In Finnish = Li | Liti | In Friulian = Li | Litiam | In Irish = Li | Litio | In Galician = Li | ליתיום | In Hebrew = Li | लिथियम | In Hindi = Li | Litij | In Croatian = Li | Lityòm | In Haitian Creole = Li | Lítium | In Hungarian = Li | Լիթիում | In Armenian = Li | Litium | In Indonesian = Li | Litio | In Ido = Li | Litín | In Icelandic = Li | Litio | In Italian = Li | リチウム | In Japanese = Li | roksodna | In Lojban = Li | ლითიუმი | In Georgian = Li | 리튬 | In Korean = Li | Lithium | In Kölsch = Li | Lîtyûm | In Kurdish = Li | Lithium | In Latin = Li | Lithium | In Letzeburgesh = Li | Litis | In Lithuanian = Li | Litijs | In Latvian = Li | Литиум | In Macedonian = Li | ലിഥിയം | In Malayalam = Li | Litium | In Malay = Li | Lithium | In Low German = Li | Lithium | In Dutch = Li | Litium | In Nynorsk = Li | Litium | In Norwegian = Li | Liti | In Occitan = Li | Lit | In Polish = Li | Lítio | In Portuguese = Li | Lityu | In Quechua = Li | Litiu | In Romanian = Li | Литий | In Russian = Li | लिथियम | In Sanskrit = Li | Litij | In Serbo-Croatian = Li | Lítium | In Slovak = Li | Litij | In Slovenian = Li | Litiumi | In Albanian = Li | Литијум | In Serbian = Li | Litium | In Swedish = Li | Lithi | In Swahili = Li | லித்தியம் | In Tamil = Li | ลิเทียม | In Thai = Li | Lityum | In Turkish = Li | Літій | In Ukrainian = Li | Litiy | In Uzbek = Li | Liti | In Vietnamese = Li | Litiom | In Walloon = Li | ליטיום | In Yiddisch = Li | 锂 | In Chinese |
In English | → Chemistry |
| LI | Lawful Interception | In English | |
| LIC | Load Interface Circuit | In English | |
| LicOB | Lick Observatory Bulletin | In English | → Serial publications, periodicals → Astronomy |
| LID | Leadless Inverted Device | In English | |
| LID | Laser-Induced Damage | In English | |
| LIDAR | Light Direction and Ranging | In English | |
| LiDAR | Light Detection And Ranging | In English | → Physics |
| LIF | Lighting Industry Federation | In English | → Organizations and associations → Environmental technology, water supply, waste management |
| LIF | Laser Induced Fluorescence | In English | → Applied sciences, technology |
| LII | Librarians' Internet Index | In English | → Libraries → Networks, communication |
| LIMBER | Language Independent Metadata Browsing of European Resources | In English | → Libraries → Computer science |
| LIMS | Logistics Inventory Management System | In English | → 00503 → Knowledge management |
| LIMS | Logistics Information Management System | In English | → Maintenance and logistics → Knowledge management |
| LINC | Logic and Information Network Compiler | In English | → Computer science |
| LINC | Library Information Network Consortium | In English | → Organizations and associations → Libraries |
| LINE | Long Interspersed Nuclear Element | In English | → Genetics |
| LINEE | Languages in a Network of European Excellence | In English | → Language, linguistics, literature |
| LINJET | Liquid Injection Electric Thruster | In English | |
| LINS | Laser Inertial Navigation System | In English | → Vehicle engineering |
| LIOS | Linz Institute for Organic Solarcells = LIOS | Linzer Institut für Organische Solarzellen | In German |
In English | → Research institutes → Energy economics |
| LIP | Land Impact Program | In English | |
| LIS | Logistics Information System | In English | → Maintenance and logistics → Knowledge management |
| LIS | Lightning Imaging Sensor | In English | → Meteorology, climatology |
| LISA | Life Science Austria | In English | → Biological sciences → Medicine |
| LISP | List Processing Language | In English | |
| LISP | LISt Processing | In English | → Programming languages |
| LIU | Line Interface Unit | In English | → Human-computer interaction |
| LJB | Libya Jamahiriya Broadcasting (http://en.ljbc.net) | In English | → Telecommunications |
| LKM | Loadable Kernel Modules | In English | → Computer science |
| LLC | Limited Liability Company | In English | → Economics |
| LLC | Library of Congress Classification | In English | → Libraries → Parliaments, representation |
| LLC | Logical Link Control | In English | |
| LLCF | Launch and Landing Computational Facility | In English | → Computer science → Spaceflight engineering, astronautics |
| LLCSC | Low-Level Computer Software Component | In English | → Software |
| LLI | Limited-Life Item | In English | |
| LLI | Laser Induced Incandescence | In English | → Electromagnetism |
| LLL | Limited-Life List | In English | |
| LLNL | Lawrence Livermore National Laboratory | In English | → Research institutes |
| LLNL | Lawrence Livermore National Laboratories | In English | → Research institutes |
| LLO | Low Lunar Orbit | In English | → Astronomy → Spaceflight engineering, astronautics |
| LLP | Launch and Landing Project | In English | → Spaceflight engineering, astronautics |
| LLPO | Launch and LAnding Project Office | In English | → Spaceflight engineering, astronautics |
| LLR | Load-Limiting Resistor | In English | |
| LLS | Launch and Landing Site | In English | → Vehicle engineering |
| LLT | Language Learning and Technology Journal (http://llt.msu.edu) | In English | → 50 → Education → Language, linguistics, literature |
| LLTE | Low-Level Treadmill Exercise | In English | → Medicine |
| LM | Laboratory Module | In English | → Research policy |
| LM | Launch Mode | In English | |
| LM | Logistics Manual | In English | → Maintenance and logistics |
| LM | Lunar Module | In English | → Spaceflight engineering, astronautics |
| LM | Logistics Manager | In English | → Maintenance and logistics |
| LM&SS | Lunar Mapping and Scientific Survey | In English | → Astronomy → Spaceflight engineering, astronautics |
| LMAM | Levenberg Marquardt with Adaptive Momentum | In English | → Mathematics |
| LMaPh | Letters in Mathematical Physics | In English | → Serial publications, periodicals → Mathematics → Physics |
| LMBO | Leveraged Management Buy Out | In English | → Finance |
| LMC | Lipid Matrix Carrier | In English | → Biochemistry, biophysics |
| LMC | Liechtenstein Musical Company | In English | → Music |
| LMC | Lean Manufacturing Consulting | In English | → Engineering, technology → Consulting |
| LMC3O | Laboratoire de Matériaux Catalytiques et Catalyse en Chimie Organique | In English | → Research institutes → Chemistry |
| LMD | Large Mirror Development | In English | → Optics |
| LMDE | Lunar Module Descent Engine | In English | → Spaceflight engineering, astronautics |
| LMDS | Logistics Management Data System | In English | → Data → Maintenance and logistics |
| LME | Launch Monitor Equipment | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
|